Townley, a 26-year-old from Brixton, was in the same carriage as the bag. He got off at Chancery Lane, his usual stop, without noticing anything amiss.

He told The Huffington Post UK he reached the end of the platform when he suddenly heard shouting about smoke coming from the bag that could be a bomb and saw a stampede of around 60 people fleeing the train and making for the exit.

Townley, who works for Inspiring Interns as a marketing manager, said: "I heard the guy who owned the bag threw it to the other side of the platform and started running as well."

Not knowing exactly what had happened, he was "swept up" in the crowd and began running. It wasn't until they reached the station's escalators to the exit that they realised it had been a false alarm.

"You just assume the worst, don't you," he said. "I didn't know to be honest what had happened. Your first thought is to try to leave, to try not to panic."

Jodi Sharp said she heard a "massive bang" and people shouted "bomb" as smoke started coming from the backpack.